In the operation of a pulp mill in the production of paper, one of the recurring problems is control of the pitch which is deposited during the operation. Pitch is the sticky, resinous substance of varying composition which originates from the extractive fraction of wood in the paper making process. Pitch is reported to be composed of fatty acids and rosin acids and their corresponding calcium, magnesium, and sodium salts. The pitch exists in its dispersed state until chemical changes in the paper furnish cause it to agglomerate and deposit on screens, felts or other paper machine surfaces. This results in holes or breaks in the sheet and expensive down time for clean ups. It is reported that the paper industry loses 30 million dollars annually because of lost production caused by pitch problems. Though various measures have been taken to combat these problems, by far the most effective measure taken to the present date is the use of talc to adsorb the pitch, thereby preventing agglomeration and subsequent deposition. The talc pitch complex is carried out as part of the final product so that no problem arises from its presence. There is discussion of this problem by Gill in "Pulp Processing", Vol. 48, No. 9 (Aug., 1974) p. 104. In addition, there is disclosed in Tappi Conference Paper: Alkaline Pulping Test 1976 a publication by Albert R. Kaiser of St. Regis Paper Company on "The Use of Talc to Control Pitch Deposition", pps. 133-134.
Use of talc as a pitch deposition control agent, however, is expensive because of the price of talc, so there is a need to increase efficiency of such pitch deposition controls, while at the same time increasing cost savings in operation of the process.